collector/mountstats: add mountpoint label for NFS metrics

Signed-off-by: Vedant-Mhatre <vedantmh@gmail.com>

Author: Vedant-Mhatre

collector/mountstats_linux.go

@@ -103,6 +103,7 @@ type nfsDeviceIdentifier struct {
 	Device       string
 	Protocol     string
 	MountAddress string
+	MountPoint   string
 }
 
 func init() {
@@ -127,9 +128,9 @@ func NewMountStatsCollector(logger *slog.Logger) (Collector, error) {
 	)
 
 	var (
-		labels      = []string{"export", "protocol", "mountaddr"}
-		opLabels    = []string{"export", "protocol", "mountaddr", "operation"}
-		translabels = []string{"export", "protocol", "mountaddr", "transport"}
+		labels      = []string{"export", "protocol", "mountaddr", "mountpoint"}
+		opLabels    = []string{"export", "protocol", "mountaddr", "mountpoint", "operation"}
+		translabels = []string{"export", "protocol", "mountaddr", "mountpoint", "transport"}
 	)
 
 	return &mountStatsCollector{
@@ -531,6 +532,7 @@ func (c *mountStatsCollector) Update(ch chan<- prometheus.Metric) error {
 			continue
 		}
 
+		mountPoint := m.Mount
 		var mountAddress string
 		if idx < len(mountsInfo) {
 			// The mount entry order in the /proc/self/mountstats and /proc/self/mountinfo is the same.
@@ -539,22 +541,22 @@ func (c *mountStatsCollector) Update(ch chan<- prometheus.Metric) error {
 		}
 
 		for k := range stats.Transport {
-			deviceIdentifier := nfsDeviceIdentifier{m.Device, stats.Transport[k].Protocol, mountAddress}
+			deviceIdentifier := nfsDeviceIdentifier{m.Device, stats.Transport[k].Protocol, mountAddress, mountPoint}
 			i := deviceList[deviceIdentifier]
 			if i {
 				c.logger.Debug("Skipping duplicate device entry", "device", deviceIdentifier)
 				break
 			}
 			deviceList[deviceIdentifier] = true
-			c.updateNFSStats(ch, stats, m.Device, stats.Transport[k].Protocol, mountAddress)
+			c.updateNFSStats(ch, stats, m.Device, stats.Transport[k].Protocol, mountAddress, mountPoint)
 		}
 	}
 
 	return nil
 }
 
-func (c *mountStatsCollector) updateNFSStats(ch chan<- prometheus.Metric, s *procfs.MountStatsNFS, export, protocol, mountAddress string) {
-	labelValues := []string{export, protocol, mountAddress}
+func (c *mountStatsCollector) updateNFSStats(ch chan<- prometheus.Metric, s *procfs.MountStatsNFS, export, protocol, mountAddress, mountPoint string) {
+	labelValues := []string{export, protocol, mountAddress, mountPoint}
 	ch <- prometheus.MustNewConstMetric(
 		c.NFSAgeSecondsTotal,
 		prometheus.CounterValue,
@@ -619,7 +621,7 @@ func (c *mountStatsCollector) updateNFSStats(ch chan<- prometheus.Metric, s *pro
 	)
 
 	for i := range s.Transport {
-		translabelValues := []string{export, protocol, mountAddress, strconv.Itoa(i)}
+		translabelValues := []string{export, protocol, mountAddress, mountPoint, strconv.Itoa(i)}
 
 		ch <- prometheus.MustNewConstMetric(
 			c.NFSTransportBindTotal,
@@ -693,7 +695,7 @@ func (c *mountStatsCollector) updateNFSStats(ch chan<- prometheus.Metric, s *pro
 	}
 
 	for _, op := range s.Operations {
-		opLabelValues := []string{export, protocol, mountAddress, op.Operation}
+		opLabelValues := []string{export, protocol, mountAddress, mountPoint, op.Operation}
 
 		ch <- prometheus.MustNewConstMetric(
 			c.NFSOperationsRequestsTotal,

collector/mountstats_linux_test.go

@@ -0,0 +1,70 @@
+// Copyright 2026 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !nomountstats
+
+package collector
+
+import (
+	"io"
+	"log/slog"
+	"strings"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+)
+
+type testMountStatsCollector struct {
+	c Collector
+}
+
+func (c testMountStatsCollector) Collect(ch chan<- prometheus.Metric) {
+	c.c.Update(ch)
+}
+
+func (c testMountStatsCollector) Describe(ch chan<- *prometheus.Desc) {
+	prometheus.DescribeByCollect(c, ch)
+}
+
+func NewTestMountStatsCollector(logger *slog.Logger) (prometheus.Collector, error) {
+	c, err := NewMountStatsCollector(logger)
+	if err != nil {
+		return testMountStatsCollector{}, err
+	}
+	return testMountStatsCollector{c: c}, nil
+}
+
+func TestMountStatsMountPointLabel(t *testing.T) {
+	*procPath = "fixtures/proc"
+
+	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
+	c, err := NewTestMountStatsCollector(logger)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	reg := prometheus.NewPedanticRegistry()
+	reg.MustRegister(c)
+
+	expected := `# HELP node_mountstats_nfs_age_seconds_total The age of the NFS mount in seconds.
+# TYPE node_mountstats_nfs_age_seconds_total counter
+node_mountstats_nfs_age_seconds_total{export="192.168.1.1:/srv/test",mountaddr="192.168.1.1",mountpoint="/mnt/nfs/test",protocol="tcp"} 13968
+node_mountstats_nfs_age_seconds_total{export="192.168.1.1:/srv/test",mountaddr="192.168.1.1",mountpoint="/mnt/nfs/test-dupe",protocol="tcp"} 13968
+node_mountstats_nfs_age_seconds_total{export="192.168.1.1:/srv/test",mountaddr="192.168.1.1",mountpoint="/mnt/nfs/test-dupe",protocol="udp"} 13968
+`
+
+	if err := testutil.GatherAndCompare(reg, strings.NewReader(expected), "node_mountstats_nfs_age_seconds_total"); err != nil {
+		t.Fatal(err)
+	}
+}